Why Your Knee and Hip Joint Hurts When Running

Your heel strike running style is the reason your knee and hip joint hurts. To understand why this happens, it is important to learn how the impact at heel strike interacts with the knee and hip joints.

Moreover, to understand how heel strike running is harmful to the body, studies have used computational models that incorporated soft tissue structures, anatomical geometry and impact formulations to quantify the boundary of impact loads at heel strike.

Why Your Knee and Hip Joint Hurts When Running

We already know that injuries caused by running are created by repetitive trauma impacts and joint overloading, making certain conditions, such as knee osteoarthritis, more likely to occur.

However, Kaplan and Heegaard (2000) found a problem with the current research on impact-related injuries in heel strike runners. They noted that most computational models only examined the support-phase of running, not the touchdown phase, which makes it more challenging to understand the interactions of the impact peak and muscular actions in heel strike running.

Incorporating the touchdown phase of heel strike running is vital because at heel strike, a measurable impact peak is generated that is not generated in a forefoot strike landing.

Because the impact peak at touchdown is strongly related to repetitive stress injury, forefoot runners are often excluded from studies on these injuries for the reason that forefoot running generates no measurable impact peak (Lierberman et al., 2010). Heel strike runners on the other hand, are studied exhaustively to understand the role of the impact peak in degenerative joint progression.

The researchers developed a model that incorporated tangential and normal compliances to investigate the ground reaction forces during the impact period of heel strike running.

Illustration from the study showing the double leg pendulum model (left) and the second model (right) used to investigate the effects of the impact peak on joint forces.

The researchers also used the double leg pendulum model to examine the ground reaction force and a second model was used to examine the ground reaction forces at the front of the foot while the back foot maintained contact.

The researchers elegantly demonstrated that at heel strike, impulsive forces were greater than impulsive external forces, indicating a higher collision force between the body and the ground at touchdown.

Unsurprisingly, their data was inline with earlier work that showed that ground reaction forces were greater than body weight during heel strike. From this, the researchers inferred that high loading at heel strike coupled with muscular action responses amplified joint reaction forces at the knee and hip. Their data is of considerable relevance because the knees and hips are highly susceptible to degenerative joint disorders in runners who are heel strikers.

Lastly, because forefoot running does not generate a measurable impact peak and many aspects of the onset of degenerative joint disorders happen with repetitive exposure to impact peaks, would it not seem to make more sense to be a forefoot runner?

BSc Neurobiology; MSc Biomechanics candidate, ultra minimalist runner & founder of RunForefoot. I was a heel striker, always injured. I was inspired by the great Tirunesh Dibaba to try forefoot running. Now, I'm injury free. This is why I launched Run Forefoot, to advocate the health & performance benefits of forefoot running and to raise awareness on the dangers of heel striking, because the world needs to know.